Nirvana changed the course of popular culture with their defining album, Nevermind. When Dave Grohl reunited with producer Butch Vig some 20 years later to make the newest Foo Fighters record, Wasting Light, it made perfect sense to invite his ex-bandmate Krist Novoselic to come down and jam.

Naturally, this led fans to speculate about the subject matter of the resulting track, "I Should Have Known."

Speaking candidly to MTV News and a group of fans assembled at the home of Shivan, a California contest winner who won the chance to have the Foo Fighters premiere their video for "Rope" in his backyard on MTV.com, Grohl explained how "I Should Have Known" came to be and how it relates to the tragic suicide of Kurt Cobain.

"When we made that record, Nevermind, it really changed everyone's lives — forever," he said. "Butch is a great guy. It was a long time ago, but we don't really feel like we've changed too much. We've seen each other over the last 20 years. We've seen each other at parties. I always kind of knew that someday I'd make another record with him, 'cause he's an amazing producer. He's great."

Vig's involvement with the Foo's forthcoming seventh studio album prompted the drummer-turned-singer/guitarist to call up his old friend Novoselic, who co-founded Nirvana with Cobain in 1987. Grohl joined the band in 1990.

"We've got a lot between us. We're very close friends," Grohl explained. "I thought, 'Wow, I'll call Krist and have him come down and jam.' At first, I don't think we had a particular song in mind; I just called him up and he was like, 'Yeah, I'll come down and do it.' The most important thing, really, was for us to hang out together, with Butch, in a studio."

"I Should Have Known," which Grohl called one of the darker songs on the record, happened a little bit later.

"With every album, if I ever sing a song about losing someone or death, most people really just sort of assume that it's about Kurt," Grohl said. "And I have wonderful memories of Kurt. Kurt was a great dude. He was a really sweet guy. And it's heartbreaking still, what happened. But unfortunately, it's happened to me more than once in my life. So when I first started writing that song, I was writing it about someone else."

The song eventually took on even broader meaning, as songs often do, beyond the initial inspiration. "The idea is really more that you don't think about the specific person or who it's about. It's just about what it's about.

"I don't want to take that connection from you because it might have happened to you," he continued. "So when you're listening to it or singing it, you're doing it for your own reasons, not mine."

Wasting Light, which also features a guest appearance from Bob Mould (whose band, Hüsker Dü, were a huge influence on Nirvana) and marks the return of guitarist Pat Smear, will be released April 12.

What do you think of the Foo Fighters' new music? Let us know in the comments!